A simple blood test that detects a form of the metal zinc soon may become available to diagnose breast cancer at its earliest and most treatable stages. Researchers at Oxford University in Britain found that breast tumors absorb a "light" form of zinc, meaning that a "heavy" form of the metal might be detectable in higher concentrations in the blood of people with early cancers.

To measure how the human body processes zinc, the researchers adapted techniques normally used for analyzing trace metal isotopes in the study of climate change and planetary formation.

It's been known for more than 10 years that there are high concentrations of zinc in cancerous breast tumors, according to Fiona Larner of Oxford's Department of Earth Sciences. But Larner, who led the research, said the molecular mechanisms that cause this have not been known.

The techniques used by scientists to detect differences in zinc isotopes in the presence of cancer are extremely sensitive, and could lead to a blood test for a cancer biomarker, or measurable indicator, possibly within the next five years.

In one of the five breast cancer patients studied, researchers also noted changes in copper composition that could be another biomarker for tumor activity.

A study looking at how the human body processes metals was published in the Royal Society of Chemistry Journal Metallomics.